He can touch it for a second (it's cool and smooth) and then it jerks back and splashes water in his face.

"Hey!" 

Mr. Wonka hopes his peals of laughter won't scare away this beautiful specimen before he can get a closer look. Oh how he loves the outdoors!!

Nah it's busy having a splash fight.

Kevin is enthusiastically splashfighting back, in total nonawareness of any philosophical questions about whether you can splash something that's already underwater. His shirt is soaked.

Behind Mr. Wonka's hoots of delight and merry blue eyes, the gears are whirring away.

Yet another wild animal showdown with this almost playful cross-species sparring. First the bug, then that angry vegetable, and now some sort of...cantankerous wild koi, he's not quite sure. Quite a range of taxa. Hm! Quite an interesting place they've found themselves in. Hm hmm!

What if he tries to GRAB the fish and hoist it OUT of the water. That would be a REVERSE SPLASH.

He can TRY. For about 0.1 seconds. The fish is very smooth and very wet.

Get hockey-checked, fish!

Get splashed on, human!

Clack clack clack goes the cheering section.

"Yes, give the old pond-gobbler what for!" squeaks Mr. Wonka.

He would love to inspect the glistening fish himself. But he wouldn't dream of intervening when things are so interesting—it would be a great injustice. This is educational, after all. He once again notes Kevin's commendable blitheness at being whisked away to a foreign wilderness and obliged to exchange stabs and blows—and maritime strikes—with the locals. Good fellow.

The fish isn't strong enough to knock Kevin over and Kevin isn't strong enough to grab the fish and keep it grabbed. Which means they stay in a stalemate long enough that Kevin eventually asks--

"Why am I wrestling a fish?"

The fish's response to this is one more rather tired splash and a sound that can't be understood from above water.

Huh. Why isn't it swimming away.

"Are we friends now, is that how this works?" Gentle patting?

Affectionate knee bonk.

Mr. Wonka watches raptly, alertly, vibratingly, as this emotional alchemy takes place.

Kevin . . . is soaking wet and very cold. He starts sloshing up the bank, water pouring out of his clothes, one eye on the fish.

Splosh splosh flop flop now there's a fish on the bank with him. It doesn't seem especially bothered by being in air, just kind of . . . floppy. Ill-adapted to terrestrial locomotion. It jackknifes and pops up in the air and plaps back down in a slightly different position, repeatedly, and this works more than none.

"Woah! I didn't know you could do that! That's honestly really impressive given how bad you are at it."

"Karp gikarp," says the fish, in a tone of philosophical detachment. Boing plap.

"Oh, splendid, splendid! We're becoming quite the menagerie!" Mr. Wonka beams. It so rarely happens in reverse like this.

"Come along, then! One of you we've got to get dry, and the other I'm certain we can find a way to keep wet. You, too, my dear bug! If you'll all just flop-plap-plop this way, quickly please."

". . . Do you want me to carry you?" Kevin asks the fish, because seriously, what.

"Magikarp!" says the magikarp and boings cheerfully into Kevin's outstretched arms.

Kevin whoofs out a breath and says "you're heavier than you look, dude," but makes it a decent fraction of the way back to camp before giving up and leaving the Magikarp to its own boingly devices.